The AEM EV Combined Charging Unit (CCU) combines both an On-Board Charger (OBC) and a DC-DC Converter (DCDC). The OBC charges the HV Battery Pack by taking 120v or 240v AC energy from the grid, converting it to high voltage DC and charging the high voltage battery in the vehicle. The DC-DC converter takes the high voltage from the battery pack and converts it to low voltage to maintain the charge in the vehicles 12V battery. The DC-DC converter performs the duties that the alternator does in an ICE vehicle. The CCU is fully controlled by the VCU via the CAN bus and the OBC and DC-DC report voltage, current and status information back to the VCU.